Tsugi no Kuuhaku wo Ume yo.

*"I never knew something could feel this good."* Kurokawa is cool and aloof, never showing his true feelings to anyone. His mysterious aura has made him quietly popular around campus. One day, Shirasaki, who shares a class with him, is asked by a group of girls to find out if Kurokawa has a girlfriend. But when Shirasaki approaches him, he notices a red lipstick mark on Kurokawa’s neck—a stark contrast to his "pure," "innocent," and "pristine" image…! (Source: Libre, translated) *Note: Includes three extra chapters.*